Pressure-Resistant Tank for Cryogenically Stored Fuel

ABSTRACT

A heat-insulated tank is provided for use as a reservoir for an operating agent of a drive assembly of a motor vehicle, particularly a heat-insulated cryotank for condensed gases. The tank consists at least of an interior tank for receiving a condensed gas, which interior tank is held in a heat-insulated manner in at least one exterior tank, which can be closed by a lid. At least one valve, a sensor, and/or a conduit connecting piece with pertaining conduits are accommodated in the insulation space, in the area of the lid between the interior tank and the exterior tank, fixedly connected with the lid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT International Application No. PCT/EP2009/003840, filed May 29, 2009, which claims priority under 35 U.S.C. §119 from German Patent Application No. DE 10 2008 026 824.0, filed Jun. 5, 2008, the entire disclosures of which are herein expressly incorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a pressure-resistant tank, particularly a cryotank, especially for the storage of condensed gas for supplying an internal-combustion engine driving a motor vehicle. With respect to the technical background, reference is made to German patent document DE 195 46 618 A1.

Fuels for driving motor vehicles, such as hydrogen or natural gas, or the like, which will be extremely interesting in the future, can in practice be stored in a relatively advantageous manner only in a liquefied and therefore considerably cooled condition. In the case of this cryogenic fuel storage, the very-low-temperature liquid hydrogen supply is stored in the vehicle in a boiling condition in the thermally very highly insulated pressure-resistant tank. In this case, by storing the hydrogen at a temperature a little above its boiling temperature at ambient pressure, approximately 20 K, the energy density of the boiling hydrogen is maximized. In the storage tanks currently technically implemented, the hydrogen is typically present at temperatures of from approximately 21K to approximately 27 K and the corresponding boiling pressures of approximately 2 bar (abs.) to approximately 5 bar (abs.). In the lower part of the storage tank, the boiling hydrogen is present as a denser liquid phase (LH2) and above the lower part as a gaseous phase (GH2).

As a rule, such storage tanks have a double-walled construction, in which case the liquid gas is stored in the interior tank, and the space between the interior tank and the exterior tank is evacuated and used for insulation. The control of the cryofuel flows and of the ancillary equipment takes place by way of removal and filling pipes as well as electric lines, and control elements arranged essentially outside the cryotank. For reducing the heat conduction into the interior tank, the removal and filling pipes are surrounded by a vacuum jacket and are constructed in a length that is suitable for reducing heat, before they enter into the interior tank.

In German published patent application DE-OS 195 46 618, a storage tank for cryogenic media is suggested where an interior-enclosing evacuated insulation space is present between the two tanks. Through this insulation space, conduits arranged in the interior tank are guided to control elements arranged outside the exterior tank. These control elements are situated in a vacuum tank which is non-detachably connected with the exterior tank. For this purpose, a tank wall of the exterior tank bounds the vacuum tank and the conduits extend through this tank wall.

Such a vacuum tank outside the exterior tank requires additional space and its connection to the exterior tank has to be established separately, which results in high manufacturing costs. In addition, it is desirable to produce a cryotank which has a light weight in a modular construction and a high degree of prefabrication.

It is an object of the present invention to indicate a corresponding solution and to provide a storage tank as desired.

According to the invention, this object is achieved by providing a heat-insulated tank for use as a reservoir for an operating agent of a drive assembly of a motor vehicle, particularly a heat-insulated cryotank for condensed gases, having an interior tank for receiving a condensed gas, which interior tank is held in a heat-insulated manner in at least one exterior tank which can be closed by way of a lid. At least one valve, sensor, and/or a conduit connecting piece with the pertaining conduits is accommodated in an insulation space in an area of the lid between the interior tank and the exterior tank, in a manner fixedly connected with the lid.

Further preferred embodiments of the invention are characterized in that, viewed in the direction of its longitudinal tank axis, the exterior tank consists at least of a circumferential wall element with a bottom, whose open opposite end can be closed by the lid. For this purpose, the cryotank may also be designed as a molded tank whose outer shell is molded essentially according to the space available in the motor vehicle.

As an alternative, the exterior tank, also as a molded tank, may also consist of at least one hollow-cylindrical circumferential wall element having a removable bottom and a removable lid. In which case, at least one additional valve, additional sensor, and/or an additional conduit connecting piece with the pertaining conduits may then also be accommodated in the insulation space in the area of the bottom between the interior tank and the exterior tank in a manner fixedly connected with the bottom.

Additional advantageous embodiments of the invention are characterized in that the conduits lead through the lid and/or the bottom out of the exterior tank. In addition, at least one conduit may be integrated on at least a portion of its length in the lid and/or in the bottom; just as a valve and/or a sensor may at least partially be integrated in the lid and/or in the bottom. In the case of a valve, it is advantageous for the latter to be integrated in the lid and/or in the bottom such that a valve seat is constructed there. The lid preferably consists of metal and is tightly connected, particularly screwed to the circumferential wall element, for example to be vacuum tight.

As a result of this construction of the cryotank, a simple series production of the tank can be implemented. The lid and/or the bottom can be completely equipped ahead of time with all fittings, i.e. connecting pieces, valves, sensors and pipe conduits, suspensions, etc. and can be subsequently placed on, attached and connected to the exterior tank which is equipped with the interior tank. All secondary systems are integrated in the lid and/or the bottom of the tank wall of the exterior tank. The valve seats form a part of the tank wall of the exterior tank and additionally strengthen this area. Reinforcements between the individual components can also have a simple construction. In this case, the connecting conduits may also be situated in the insulation space. In addition, the valves and the sensors in the lid and/or the bottom are easily accessible and exchangeable. Within the lid and/or the bottom, the valves can also be connected or networked by boreholes, so that a valve block is created analogous to the hydraulic system. The interior tank bearing can also be a component of the lid and/or of the bottom, for example, by way of a receiving part.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial spatial view of an exterior tank of a cryotank according to an embodiment of the invention for storing a cryogenic medium;

FIG. 2 is a partial spatial view of an exterior tank of a cryotank according to an embodiment of the invention for storing a cryogenic medium; and

FIG. 3 is a view of the exterior tank in a partial section view without a covering of the lid.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view with a lid covering; FIG. 2 is a view without a lid covering. FIG. 3 is a view of the exterior tank in a partial sectional view without a lid covering. In all figures, the same elements are indicated by identical reference numbers.

A cryotank having an interior tank (not shown) according to FIGS. 1 to 3, for storing liquid hydrogen LH2 is installed in a motor vehicle (not shown). This liquid hydrogen LH2 is used as a fuel for supplying an internal-combustion engine, which drives the motor vehicle. The cryotank is an oblong tank, consisting of a pressure-resistant interior tank, disposed by way of a bearing device in an exterior tank, with an insulation layer—a vacuum—disposed in-between. By means of such a so-called molded tank, named on the basis of its circumferential design corresponding to the installation space condition in the motor vehicle, it becomes possible to minimize the spaces between the cryotank and the neighboring vehicle parts and thereby maximize the volume of the interior tank of the cryotank by a better utilization of the space in the vehicle.

The thus designed exterior tank 1, for receiving the interior tank filled with condensed gas and held in a heat-insulated manner in the exterior tank, consists of a hollow-cylindrical circumferential wall element 2 having a bottom (not shown) and a lid 3 that can be placed thereon at the open end opposite the bottom in the direction of the longitudinal tank axis. The circumferential wall element 2 of the exterior tank and the lid may be produced of a metallic and/or non-metallic material and are tightly connected with one another, particularly by welding or screwing together. Likewise, the lid may consist of a dense interior layer, particularly made of metal, surrounded at least on the outside by at least one reinforcing layer made of fiber material and, in the joined condition may be surrounded at least at the joining points, at least on the outside, by an additional reinforcing layer made of fiber material.

In the insulation space 4, in the area of the lid 3 between the interior tank and the exterior tank 1, fixedly connected with the lid 3, two cold valves 21 are accommodated for the refueling and venting, with pertaining conduits 22 which lead to the interior tank. Additional conduits 6 accommodated there are guided from the interior tank by way of the lid 3 out of the exterior tank 1. For this purpose, conduit connecting pieces, valves and sensors are mounted in the lid 3. Five valves,—a shut-off valve 5 of the consuming device supply conduit, two safety valves 9, 10, a control valve 11 and a boil-off pressure control valve 12—are each integrated between honeycomb-shaped reinforcing ribs 7 in the lid 3 such that the respective valve seats are constructed in the wall of the exterior tank 1 of the lid 3. The pertaining valve bodies are then each screwed together in a honeycomb 8 made of reinforcing ribs 7 of the lid 3, just like a tank fastening 13 for the exterior tank 1, two pressure sensors 14, 15 and a temperature sensor 16. One conduit connecting piece respectively for the filling pipe 17, for two safety conduits 18, 19, for the consuming device supply conduit 20 and for the boil-off pressure control conduit 21, are also each screwed together in a honeycomb 8 made of reinforcing ribs 7 of the lid 3. A superimposable lid covering 23 closes off the described fittings accommodated in the lid 3.

By means of this construction, a series production of the cryotank can be implemented. The lid 3 can be equipped ahead of time with conduit connecting pieces, valves and sensors and can be assembled. Subsequently, the lid 3 is inserted into the exterior tank 1 and is tightly joined. This results in a molded tank of a light weight and a high degree of prefabrication which can be manufactured in a cost-effective manner of a reliable quality.

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof. 

1. A heat-insulated tank for use as a reservoir for an operating agent of a drive assembly of a motor vehicle, the heat-insulated tank comprising: an interior tank for receiving a condensed gas; an exterior tank in which the interior tank is arranged in a heat-insulated manner; a lid operatively configured to close the exterior tank; at least one of a valve, a sensor, and a conduit connector with an associated conduit, being fixedly connected with the lid; wherein the at least one of the valve, the sensor, and the conduit connector with the associated conduit are configured so as to be arranged in an insulation space in an area of the lid between the interior tank and the exterior tank.
 2. The heat-insulated tank according to claim 1, wherein the tank is a heat-insulated cryotank for the condensed gas.
 3. The heat-insulated tank according to claim 1, wherein, viewed in a longitudinal tank axis direction, the exterior tank comprises a circumferential wall with a bottom and an open end opposite the bottom, the open end being closable by the lid.
 4. The heat-insulated tank according to claim 3, wherein the heat-insulated tank is a molded tank.
 5. The heat-insulated tank according to claim 1, wherein the exterior tank comprises at least one hollow-cylindrical circumferential wall with a removable bottom and a removable lid.
 6. The heat-insulated tank according to claim 5, further comprising: at least one of an additional valve, an additional sensor, and an additional conduit connector with an associated conduit is fixedly connected with the bottom, the at least one of the additional valve, the additional sensor, and the additional conduit connector with the associated conduit being arranged in the insulation space in a bottom area between the interior tank and the exterior tank.
 7. The heat-insulated tank according to claim 6, wherein the associated conduits extend out of the exterior tank through at least one of the lid and the bottom.
 8. The heat-insulated tank according to claim 6, wherein at least one of the associated conduits is integrated along a portion of its length in at least one of the lid and the bottom.
 9. The heat-insulated tank according to claim 6, wherein at least one of the valve, the additional valve, the sensor, and the additional sensor is integrated partially in at least one of the lid and the bottom.
 10. The heat-insulated tank according to claim 9, wherein the at least one valve and the additional valve integrated in at least one of the lid and the bottom provides a valve seat constructed in the at least one of the lid and the bottom.
 11. The heat-insulated tank according to claim 3, wherein the lid is a metal lid connected to the circumferential wall.
 12. The heat-insulated tank according to claim 11, wherein the lid is vacuum tight screwed to the circumferential wall to form the connection. 